This invention relates to a key-driving/detecting mechanism for performing automatically a keyboard instrument.
An automatic musical instrument has already been proposed wherein an automatic performance capability is provided for such keyboard instruments as a grand piano or an upright piano so as to enable an automatic performance in addition to a manual performance. One example of such musical instrument is disclosed in U.S. Pat. No. 3,160,052 issued on Dec. 8, 1964. According to this patent generally horizontal recessed surfaces are formed on the fore end of a generally horizontal bed frame, and a key-driving/detecting mechanism is disposed between the recess surfaces and respective keys. When the frame is worked so as to mount the key-driving mechanism the balance among the strength of the strings connected under tension to the piano frame may be disturbed. Especially, in recent years for the purpose of improving soundproof effect, a key bed is usually made of a polywood construction in which a layer of polyurethane is sandwiched between wood plates. Such key bed is impossible to work in a manner as above described due to its low mechanical strength so that it is essential to work the key bed and to reinforce the same.
When the frame is worked as above described and then incorporated into a piano already assembled with the key-driving mechanism from the rear side, it is difficult to form the recess surfaces.
In the prior art key-driving mechanism, an armature is pulled into a central opening of a solenoid coil secured on the frame on depressing a key. In this construction, however, alignment of the positions of the armature and the solenoid coil is troublesome.